Most rich countries besides the US have hit on a surprisingly simple approach to reducing child poverty: just giving parents money.
This idea, known as a child benefit or child allowance, exists in almost every EU country as well as in Canada and Australia. In many countries, the payments are truly universal; you get the money no matter how much you earn. In others, like Canada, the payments phase out for top earners but almost everyone else benefits. France has a weird scheme where only families with two or more children get benefits, as an incentive to have more kids.
But the core principle is the same in every system: Low and middle-income families are entitled to substantial cash benefits to help them raise their children.